/* epd_font.c */

/* Includes */
#include "epd.h"
#include "epd_font.h"
#include "epd_fonts.h"
#include "util.h"

/* Definitions */
#define EPD_FONT_DATA_STRUCT_SIZE 23
#define epd_pgm_read(adr) (*(const uint8_t *) (adr))

/* Function Prototypes */
static void epd_read_fontcfg(epd_fontcfg_t *cfg, epd_font_t *font);
static uint8_t epd_font_get_byte(epd_font_t *font, uint8_t offset);
static uint16_t epd_font_get_word(epd_font_t *font, uint8_t offset);
static void epd_update_ref_height(epd_t *epd);
static uint16_t epd_ascii_next(UNUSED epd_t *epd, uint8_t b);
static uint16_t epd_utf8_next(epd_t *epd, uint8_t b);
static uint8_t epd_draw_string(epd_t *epd, uint32_t x, uint32_t y, const char *str);
static uint8_t epd_draw_glyph(epd_t *epd, uint32_t x, uint32_t y, uint16_t encoding);
static uint8_t epd_font_draw_glyph(epd_t *epd, uint32_t x, uint32_t y, uint16_t encoding);
epd_font_t *epd_font_get_glyph_data(epd_t *epd, uint16_t encoding);
static int8_t epd_font_decode_glyph(epd_t *epd, const uint8_t *glyph_data);
static void epd_font_setup_decode(epd_t *epd, const uint8_t *glyph_data);
static int8_t epd_font_decode_get_signed_bits(epd_font_decode_t *f, uint8_t cnt);
static uint8_t epd_font_decode_get_unsigned_bits(epd_font_decode_t *f, uint8_t cnt);
static void epd_font_decode_len(epd_t *epd, uint8_t len, uint8_t is_foreground);

/* Function Definitions */
void epd_font_set(epd_t *epd, epd_font_t *font)
{
	if(epd->font != font)
	{
		epd->font = font;
		epd_read_fontcfg(&(epd->fontdata.cfg), font);
		epd_update_ref_height(epd);
	}
}

static void epd_read_fontcfg(epd_fontcfg_t *cfg, epd_font_t *font)
{
	/* offset 0 */
	cfg->glyph_cnt            = epd_font_get_byte(font,  0);
	cfg->bbx_mode             = epd_font_get_byte(font,  1);
	cfg->bits_per_0           = epd_font_get_byte(font,  2);
	cfg->bits_per_1           = epd_font_get_byte(font,  3);

	/* offset 4 */
	cfg->bits_per_char_width  = epd_font_get_byte(font,  4);
	cfg->bits_per_char_height = epd_font_get_byte(font,  5);
	cfg->bits_per_char_x      = epd_font_get_byte(font,  6);
	cfg->bits_per_char_y      = epd_font_get_byte(font,  7);
	cfg->bits_per_delta_x     = epd_font_get_byte(font,  8);

	/* offset 9 */
	cfg->max_char_width       = epd_font_get_byte(font,  9);
	cfg->max_char_height      = epd_font_get_byte(font, 10);
	cfg->x_offset             = epd_font_get_byte(font, 11);
	cfg->y_offset             = epd_font_get_byte(font, 12);

	/* offset 13 */
	cfg->ascent_A             = epd_font_get_byte(font, 13);
	cfg->descent_g            = epd_font_get_byte(font, 14);
	cfg->ascent_para          = epd_font_get_byte(font, 15);
	cfg->descent_para         = epd_font_get_byte(font, 16);

	/* offset 17 */
	cfg->start_pos_upper_A    = epd_font_get_word(font, 17);
	cfg->start_pos_lower_a    = epd_font_get_word(font, 19);

#ifdef EPD_WITH_UNICODE
	/* offset 21 */
	fontcfg->start_pos_unicode    = epd_font_get_word(font, 21);
#endif
}

static uint8_t epd_font_get_byte(epd_font_t *font, uint8_t offset)
{
	font += offset;
	return epd_pgm_read(font);
}

static uint16_t epd_font_get_word(epd_font_t *font, uint8_t offset)
{
	uint16_t pos;

	font += offset;
	pos = epd_pgm_read(font);
	font++;
	pos <<= 8;
	pos += epd_pgm_read(font);

	return pos;
}

static void epd_update_ref_height(epd_t *epd)
{
	return_if_fail(epd->font);

	epd->fontdata.ref_ascent = epd->fontdata.cfg.ascent_A;
	epd->fontdata.ref_descent = epd->fontdata.cfg.descent_g;
	if(epd->fontdata.height_mode == EPD_FONT_HEIGHT_MODE_TEXT)
	{
	}
	else if(epd->fontdata.height_mode == EPD_FONT_HEIGHT_MODE_XTEXT)
	{
		if(epd->fontdata.ref_ascent < epd->fontdata.cfg.ascent_para)
		{
			epd->fontdata.ref_ascent = epd->fontdata.cfg.ascent_para;
		}
		if(epd->fontdata.ref_descent > epd->fontdata.cfg.descent_para)
		{
			epd->fontdata.ref_descent = epd->fontdata.cfg.descent_para;
		}
	}
	else
	{
		if(epd->fontdata.ref_ascent < epd->fontdata.cfg.max_char_height + epd->fontdata.cfg.y_offset)
		{
			epd->fontdata.ref_ascent = epd->fontdata.cfg.max_char_height + epd->fontdata.cfg.y_offset;
		}
		if(epd->fontdata.ref_descent > epd->fontdata.cfg.y_offset)
		{
			epd->fontdata.ref_descent = epd->fontdata.cfg.y_offset;
		}
	}
}

uint8_t epd_draw_str(epd_t *epd, uint32_t x, uint32_t y, const char *str)
{
	epd->fontdata.char_cb = epd_ascii_next;
	return epd_draw_string(epd, x, y, str);
}

uint8_t epd_draw_utf8(epd_t *epd, uint32_t x, uint32_t y, const char *str)
{
	epd->fontdata.char_cb = epd_utf8_next;
	return epd_draw_string(epd, x, y, str);
}

static uint16_t epd_ascii_next(UNUSED epd_t *epd, uint8_t b)
{
	if(b == 0 || b == '\n') /* '\n' terminates the string to support the string list procedures */
	{
		return 0xffff; /* end of string detected*/
	}

	return b;
}

/*
	pass a byte from an utf8 encoded string to the utf8 decoder state machine
	returns
		0xfffe: no glyph, just continue
		0xffff: end of string
		anything else: The decoded encoding
*/
static uint16_t epd_utf8_next(epd_t *epd, uint8_t b)
{
	if(b == 0 || b == '\n') /* '\n' terminates the string to support the string list procedures */
	{
		return 0xffff; /* end of string detected, pending UTF8 is discarded */
	}
	if(epd->fontdata.utf8_state == 0)
	{
		if(b >= 0xfc) /* 6 byte sequence */
		{
			epd->fontdata.utf8_state = 5;
			b &= 0x01;
		}
		else if(b >= 0xf8)
		{
			epd->fontdata.utf8_state = 4;
			b &= 0x03;
		}
		else if(b >= 0xf0)
		{
			epd->fontdata.utf8_state = 3;
			b &= 0x07;
		}
		else if(b >= 0xe0)
		{
			epd->fontdata.utf8_state = 2;
			b &= 0x0f;
		}
		else if(b >= 0xc0)
		{
			epd->fontdata.utf8_state = 1;
			b &= 0x1f;
		}
		else
		{
			/* do nothing, just use the value as encoding */
			return b;
		}
		epd->fontdata.encoding = b;
		return 0xfffe;
	}
	else
	{
		epd->fontdata.utf8_state--;
		/* The case b < 0x080 (an illegal UTF8 encoding) is not checked here. */
		epd->fontdata.encoding <<= 6;
		b &= 0x3f;
		epd->fontdata.encoding |= b;
		if(epd->fontdata.utf8_state != 0)
		{
			return 0xfffe; /* nothing to do yet */
		}
	}

	return epd->fontdata.encoding;
}

/* reset the internal state machine */
void epd_utf8_init(epd_t *epd)
{
	epd->fontdata.utf8_state = 0;
}

static uint8_t epd_draw_string(epd_t *epd, uint32_t x, uint32_t y, const char *str)
{
	uint16_t e;
	uint8_t delta, sum;
	epd_utf8_init(epd);
	sum = 0;
	for(;;)
	{
		e = epd->fontdata.char_cb(epd, (uint8_t) *str);
		if(e == 0xffff)
			break;
		str++;
		if(e != 0xfffe)
		{
			delta = epd_draw_glyph(epd, x, y, e);

#ifdef EPD_WITH_FONT_ROTATION
			switch(epd->fontdata.decode.dir)
			{
	case 0:
		x += delta;
		break;
	case 1:
		y += delta;
		break;
	case 2:
		x -= delta;
		break;
	case 3:
		y -= delta;
		break;
			}

			/*
			// requires 10 bytes more on avr
			x = epd_add_vector_x(x, delta, 0, epd->fontdata.decode.dir);
			y = epd_add_vector_y(y, delta, 0, epd->fontdata.decode.dir);
			*/

#else
			x += delta;
#endif

			sum += delta;
		}
	}
	return sum;
}

static uint8_t epd_draw_glyph(epd_t *epd, uint32_t x, uint32_t y, uint16_t encoding)
{
#ifdef EPD_WITH_FONT_ROTATION
	switch(epd->fontdata.decode.dir)
	{
		case 0:
			y += epd->font_calc_vref(epd);
			break;
		case 1:
			x -= epd->font_calc_vref(epd);
			break;
		case 2:
			y -= epd->font_calc_vref(epd);
			break;
		case 3:
			x += epd->font_calc_vref(epd);
			break;
	}
#else
	/* FIXME */
	/* y += epd->font_calc_vref(epd); */
#endif
	return epd_font_draw_glyph(epd, x, y, encoding);
}

static uint8_t epd_font_draw_glyph(epd_t *epd, uint32_t x, uint32_t y, uint16_t encoding)
{
	uint8_t dx = 0;
	epd->fontdata.decode.target_x = x;
	epd->fontdata.decode.target_y = y;
	//epd->fontdata.decode.is_transparent = is_transparent; this is already set
	//epd->fontdata.decode.dir = dir;
	const uint8_t *glyph_data = epd_font_get_glyph_data(epd, encoding);
	if(glyph_data != NULL)
	{
		dx = epd_font_decode_glyph(epd, glyph_data);
	}
	return dx;
}

/*
  Description:
    Find the starting point of the glyph data.
  Args:
    encoding: Encoding (ASCII or Unicode) of the glyph
  Return:
    Address of the glyph data or NULL, if the encoding is not avialable in the font.
*/
epd_font_t *epd_font_get_glyph_data(epd_t *epd, uint16_t encoding)
{
	epd_font_t *font = epd->font;
	font += EPD_FONT_DATA_STRUCT_SIZE;

	if(encoding <= 255)
	{
		if(encoding >= 'a')
		{
			font += epd->fontdata.cfg.start_pos_lower_a;
		}
		else if(encoding >= 'A')
		{
			font += epd->fontdata.cfg.start_pos_upper_A;
		}

		for(;;)
		{
			if(epd_pgm_read(font + 1) == 0)
			{
				break;
			}
			if(epd_pgm_read(font) == encoding)
			{
				return font + 2;	/* skip encoding and glyph size */
			}
			font += epd_pgm_read(font + 1);
		}
	}
#ifdef EPD_WITH_UNICODE
	else
	{
		uint16_t e;
		const uint8_t *unicode_lookup_table;

		font += epd->fontdata.cfg.start_pos_unicode;
		unicode_lookup_table = font;

		/* issue 596: search for the glyph start in the unicode lookup table */
		do
		{
			font += epd_font_get_word(unicode_lookup_table, 0);
			e = epd_font_get_word(unicode_lookup_table, 2);
			unicode_lookup_table+=4;
		} while(e < encoding);

		for(;;)
		{
			e = epd_pgm_read(font);
			e <<= 8;
			e |= epd_pgm_read(font + 1);

			if(e == 0)
	break;

			if(e == encoding)
			{
	return font+3;	/* skip encoding and glyph size */
			}
			font += epd_pgm_read(font + 2);
		}
	}
#endif

	return NULL;
}

/*
	Description:
		Decode and draw a glyph.
	Args:
		glyph_data: 					Pointer to the compressed glyph data of the font
		epd->fontdata.decode.target_x		X position
		epd->fontdata.decode.target_y		Y position
		epd->fontdata.decode.is_transparent	Transparent mode
	Return:
		Width (delta x advance) of the glyph.
	Calls:
		epd_font_decode_len()
*/
/* optimized */
int8_t epd_font_decode_glyph(epd_t *epd, const uint8_t *glyph_data)
{
	uint8_t a, b;
	int8_t x, y;
	int8_t d;
	int8_t h;
	epd_font_decode_t *decode = &(epd->fontdata.decode);

	epd_font_setup_decode(epd, glyph_data);     /* set values in epd->fontdata.decode data structure */
	h = epd->fontdata.decode.glyph_height;

	x = epd_font_decode_get_signed_bits(decode, epd->fontdata.cfg.bits_per_char_x);
	y = epd_font_decode_get_signed_bits(decode, epd->fontdata.cfg.bits_per_char_y);
	d = epd_font_decode_get_signed_bits(decode, epd->fontdata.cfg.bits_per_delta_x);

	if(decode->glyph_width > 0)
	{
#ifdef EPD_WITH_FONT_ROTATION
		decode->target_x = epd_add_vector_x(decode->target_x, x, -(h+y), decode->dir);
		decode->target_y = epd_add_vector_y(decode->target_y, x, -(h+y), decode->dir);

		//epd_add_vector(&(decode->target_x), &(decode->target_y), x, -(h+y), decode->dir);

#else
		decode->target_x += x;
		decode->target_y -= h+y;
#endif
		//epd_add_vector(&(decode->target_x), &(decode->target_y), x, -(h+y), decode->dir);

#ifdef EPD_WITH_INTERSECTION
		{
			uint32_t x0, x1, y0, y1;
			x0 = decode->target_x;
			y0 = decode->target_y;
			x1 = x0;
			y1 = y0;

#ifdef EPD_WITH_FONT_ROTATION
			switch(decode->dir)
			{
			case 0:
				x1 += decode->glyph_width;
				y1 += h;
				break;
			case 1:
				x0 -= h;
				x0++; /* shift down, because of assymetric boundaries for the interseciton test */
				x1++;
				y1 += decode->glyph_width;
				break;
			case 2:
				x0 -= decode->glyph_width;
				x0++; /* shift down, because of assymetric boundaries for the interseciton test */
				x1++;
				y0 -= h;
				y0++; /* shift down, because of assymetric boundaries for the interseciton test */
				y1++;
				break;
			case 3:
				x1 += h;
				y0 -= decode->glyph_width;
				y0++; /* shift down, because of assymetric boundaries for the interseciton test */
				y1++;
				break;
			}
#else /* EPD_WITH_FONT_ROTATION */
			x1 += decode->glyph_width;
			y1 += h;
#endif

			if(epd_IsIntersection(epd, x0, y0, x1, y1) == 0)
	return d;
		}
#endif /* EPD_WITH_INTERSECTION */

		/* reset local x/y position */
		decode->x = 0;
		decode->y = 0;

		/* decode glyph */
		for(;;)
		{
			a = epd_font_decode_get_unsigned_bits(decode, epd->fontdata.cfg.bits_per_0);
			b = epd_font_decode_get_unsigned_bits(decode, epd->fontdata.cfg.bits_per_1);
			do
			{
				epd_font_decode_len(epd, a, 0);
				epd_font_decode_len(epd, b, 1);
			} while(epd_font_decode_get_unsigned_bits(decode, 1) != 0);

			if(decode->y >= h)
			{
				break;
			}
		}

		/* restore the epd draw color, because this is modified by the decode algo */
		epd->draw_color = decode->fg_color;
	}
	return d;
}

static void epd_font_setup_decode(epd_t *epd, const uint8_t *glyph_data)
{
	epd_font_decode_t *decode = &(epd->fontdata.decode);
	decode->decode_ptr = glyph_data;
	decode->decode_bit_pos = 0;

	/* 8 Nov 2015, this is already done in the glyph data search procedure */
	/*
	decode->decode_ptr += 1;
	decode->decode_ptr += 1;
	*/

	decode->glyph_width = epd_font_decode_get_unsigned_bits(decode, epd->fontdata.cfg.bits_per_char_width);
	decode->glyph_height = epd_font_decode_get_unsigned_bits(decode, epd->fontdata.cfg.bits_per_char_height);

	decode->fg_color = epd->draw_color;
	decode->bg_color = (decode->fg_color == 0 ? 1 : 0);
}

/*
		2 bit --> cnt = 2
			-2,-1,0. 1

		3 bit --> cnt = 3
			-2,-1,0. 1
			-4,-3,-2,-1,0,1,2,3

			if(x < 0)
	r = bits(x-1)+1;
		else
	r = bits(x)+1;

*/
/* optimized */
static int8_t epd_font_decode_get_signed_bits(epd_font_decode_t *f, uint8_t cnt)
{
	int8_t v, d;
	v = (int8_t)epd_font_decode_get_unsigned_bits(f, cnt);
	d = 1;
	cnt--;
	d <<= cnt;
	v -= d;
	return v;
	//return (int8_t)epd_font_decode_get_unsigned_bits(f, cnt) - ((1<<cnt)>>1);
}

/* optimized */
static uint8_t epd_font_decode_get_unsigned_bits(epd_font_decode_t *f, uint8_t cnt)
{
	uint8_t val;
	uint8_t bit_pos = f->decode_bit_pos;
	uint8_t bit_pos_plus_cnt;

	val = epd_pgm_read(f->decode_ptr);

	val >>= bit_pos;
	bit_pos_plus_cnt = bit_pos;
	bit_pos_plus_cnt += cnt;
	if(bit_pos_plus_cnt >= 8)
	{
		f->decode_ptr++;
		val |= epd_pgm_read(f->decode_ptr) << (8 - bit_pos);
		bit_pos_plus_cnt -= 8;
	}
	val &= (1U << cnt) - 1;

	f->decode_bit_pos = bit_pos_plus_cnt;
	return val;
}

/*
	Description:
		Draw a run-length area of the glyph. "len" can have any size and the line
		length has to be wrapped at the glyph border.
	Args:
		len: 					Length of the line
		is_foreground			foreground/background?
		epd->fontdata.decode.target_x		X position
		epd->fontdata.decode.target_y		Y position
		epd->fontdata.decode.is_transparent	Transparent mode
	Return:
		-
	Calls:
		epd_Draw90Line()
	Called by:
		epd_font_decode_glyph()
*/
/* optimized */
static void epd_font_decode_len(epd_t *epd, uint8_t len, uint8_t is_foreground)
{
	uint8_t cnt; /* total number of remaining pixels, which have to be drawn */
	uint8_t rem; 	/* remaining pixel to the right edge of the glyph */
	uint8_t current; /* number of pixels, which need to be drawn for the draw procedure */
		/* current is either equal to cnt or equal to rem */

	/* local coordinates of the glyph */
	uint8_t lx,ly;

	/* target position on the screen */
	uint16_t x, y;

	epd_font_decode_t *decode = &(epd->fontdata.decode);

	cnt = len;

	/* get the local position */
	lx = decode->x;
	ly = decode->y;

	for(;;)
	{
		/* calculate the number of pixel to the right edge of the glyph */
		rem = decode->glyph_width;
		rem -= lx;

		/* calculate how many pixel to draw. This is either to the right edge */
		/* or lesser, if not enough pixel are left */
		current = rem;
		if(cnt < rem)
			current = cnt;

		/* now draw the line, but apply the rotation around the glyph target position */
		//epd_font_decode_draw_pixel(epd, lx,ly,current, is_foreground);

		/* get target position */
		x = decode->target_x;
		y = decode->target_y;

		/* apply rotation */
#ifdef EPD_WITH_FONT_ROTATION

		x = epd_add_vector_x(x, lx, ly, decode->dir);
		y = epd_add_vector_y(y, lx, ly, decode->dir);

		//epd_add_vector(&x, &y, lx, ly, decode->dir);

#else
		x += lx;
		y += ly;
#endif

		/* draw foreground and background (if required) */
		if(is_foreground)
		{
			epd->draw_color = decode->fg_color; /* draw_color will be restored later */
			epd_draw_line(epd,
			              x,
			              y,
			              current,
#ifdef EPD_WITH_FONT_ROTATION
			              decode->dir
#else
			              EPD_DIR_L2R
#endif
			);
		}
		else if(decode->is_transparent == 0)
		{
			epd->draw_color = decode->bg_color; /* draw_color will be restored later */
			epd_draw_line(epd,
			              x,
			              y,
			              current,
#ifdef EPD_WITH_FONT_ROTATION
			              decode->dir
#else
			              EPD_DIR_L2R
#endif
			);
		}

		/* check, whether the end of the run length code has been reached */
		if(cnt < rem)
		{
			break;
		}
		cnt -= rem;
		lx = 0;
		ly++;
	}
	lx += cnt;

	decode->x = lx;
	decode->y = ly;
}